A report in the American Journal of Human Biology, revealed that in the U.S. where women outnumbered men, their babies were below the ideal healthy weight range. With a study at the University of Michigan, they found that on average, babies weighed less than 5.5 pounds based off population and birth records from 2000.
Calling this the “Life history trade-off,” they are referring to the evolutionary biological phenomena where if men are fewer than women, they are less likely to help raise children. The women, in turn, are forced to balance both raising their children and providing for the family, along with preserving enough energy to allow their body to reproduce again.
Ultimately, women in this situation can tend to eat less while they are pregnant and end up having premature births. If the mother is put through fewer weeks of pregnancy, they are simultaneously avoiding delivering a larger baby and the complications that go along with that. To avoid this dilemma, MEN, stay around to help raise the babies you have fathered.